RFR: 8351876: RISC-V: enable and fix some float round tests

[Hamlin Li]

Hi,
Can you help to review this simple patch?
It's a follow-up of https://github.com/openjdk/jdk/pull/23985.

Thanks

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Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/24015/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24015&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351876
  Stats: 13 lines in 2 files changed: 8 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/24015.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24015/head:pull/24015

PR: https://git.openjdk.org/jdk/pull/24015